Metallurgical process



April s, 1926. www

^ W. E. GREENAWALT METALLURGICAL PROCES S Filed Jan. 27. 1925 Copper 501 ultiem Copper Soluhn lil lill

l is u. n E

Application filed January 27, 1225. Serial- No, .'Lill,

To all whom may concern:

Be' it known 'that I, il/'nalaat E, GassnewaL'r, a citizen ci' the United States, residing` in the city and county of Denver and State oi' Colorado, have invented certain new and useful improvements in Metallurgical Processes, ot which the following is a specification My invention relates to metallurgical processes, and has as its obiect the eifective extraction oi metals-especially copperfrom their ores and concentrates.

The invention will be. described more particularly in its application to the extraction of copper' from its ores, although it will be understood that it is applicable to the extraction olf other njictals, such as goldgsilver, lead, zinc, etc;

Itlias been observed'in leaching copper and other `ores, especially with an acid solution, "that ,most of the copper is quickly dissolved, and a considerable amount ot very line slime is formed as a result of the chemical action on 'the ore. This is largely, although not entirely, due to the iiormatipn oi calcium sulphate as a result ot' the acid acting on the slime which is always more or less associated with copper ores. This slime, together with the lines produced by crushingl the ore 'to the desired iineness .tor eilectlve treatment, makes it diiiicult, and in most cases quite impractical, to treat copper ore with an acid solution by percolation. The fines produced by. the crushing, together with the shines formed by the chemical reactions in leaching, clog the interstices of the ore charge and retards the percolation to an impractical degree.

lt has been observed that the copper in the lines produced by crushing, is quickly dissolved, say in a. iiew hours, while the copper in the sands, or coarser material, usually requires a much longer time for satisfactory extraction,usually several days, and sometimes several Weeks, especially ii 'sonic oi' the copper is in the torni ot' sulphide, such as chalcocite, or in the form ot a silicate, such chrysocolla, when a considerable time is required to make a satisfactory extraction ol: the copper by leaching.

lt has also been frequently observed, in treating high grade ore or concentrate by percolation witlran acid solution, that the solution quite likely lo become so charged with copper sulphate, that the sulphate cryslallires in the charge and stops 'further percolation. lll/'hen' this happens, the charge has to be removed frointhe tank and the diiliculty remedied before further progress can be made. This is true, as to crystallization, either with sulphate or chloride solutions, and great care is required in percolating a rich coppei ore charge that, the solution is maintained suiiiciently dilute in both acid and copper te avoid crystallization of the copper salt in the ore mass.

It has also been observed thatd ii' the ore is given a preliminary treatment, say by agitation, most of the copper can be extracted Yin a comparatively ,short tiine, and l that most of the slime that lvrill forni due to the action ot the acid on the ore, will be formed during this 'short preliminary treat'- ment, and that if trie sands or eoarser ina terial is then separated from the lines and slimcs, con'iparatively little more slime will he formed by prolonged treatment, and that the'ore, stripped of its excessive lines and slinies, may then be percolated quite satisfactorily to the extent desired to get a very high extraction ot the copper fromthe sands.

The present process is based on these olosei-"ations, and it can best be described by referring to the accompanying drawing, which is a flow sheet in diagrammatic plan, and illustrates the preferred method 0i' carrying` it out.

The fresh orc, crushed to suitable linensss for i tisi'actiory treatinientJ by agitation, say Afrom l to 12 mesh, is fed into agitator No. l in a regulated stream, determined by capacity of the plant, where it is agitated with copper solution from the treatment of previous charges, in agitators No. 2 and lilo. 5l. agitator No. 3, where it is agitated with 'the partly treated ore trom agitators No, l and No. 2. llsch agitation unit comprises an agitator and a separator, and a good working plant will usually'colnprise a number or' not desired, although the process will ivorlr The. strong acid solution is fed into all fill

solution, or pulp, flows :.m into rio. l,

Where the orc elution are separated. This seperatio not ne complete, and

can oe made an ordinary separator, or thickener, commonly used for such purposes. The: copper solution flows into settler No. 1., Where 1t is clariiied and stored tor further treatment, as desired. The thickened pulp from separator o. flows into the agitator No. 2, Where it is given further treatment with the solution containing copper und acid from separator No. 3. The agitated mixture then Hows into separator No. 2, where the ore and solution are again separated. as in unit No. l. The solution flows into agitator No. l, While the thickened pulp flous into agitator No. 3. where the agitation is re cated with fresh aci'd solution, preteraby obtained by the precipitation o the copper from the leach solution by electrolysis. The agitated pulp from agitator No. 3 iows into separator No. 3, and the process is so regulated that the pulp flowing into separator No. 3 will be sutliciently treated, both with respect to the extraction ot the copper and the formation o siii-aes, that the subsequent steps may be carried out eflvantageously as determined by experience for each particular ore.

The copper solution from separator No. flows into agitator No. 2, and the ore pulp flows into a classitier, in which the ore fines and slimes are separated from the sands. .its is well known, these classifiers can he adapted to make an)v desired separation between the slimes and the sands, as experience will dictate for any particular ore. Usually, considerable amount of fines, but not slimcs, can go with the sands, Without seriously interfering with the subsequent percolation of the sands. The sands are flowed into the percolation tanks No. 1 and No. 2, `for `further treatment by percolation.

The slime )nlp flows into separator No. 4 where the riclier copper solution is separated from the slime, and the copper solution so sepa 'ated flows into agitator No. 3, with fresh acid solution, und is gradually worked up to rich copper solution for the regular precipitation of the copper. The residualslime is Washed, as in separator No. 5. and may be Wasted, or given further treatment hy otation if the slime contains tine sulphides and then Wasted. The lean copper solution, or wash water. flows into settler No. 2, Where il is stored and clarified. after which it is preriiliitatcd with a suitahlichemical reagent. such metallic iron or hydrogen sulphide, pretcrabl)v with hydrogen sulphide in the HES prccipitalor. vEhe mixture` of liquid and CnS precipitate flows into separator No. G. where the CnS is sepurated from the lean or foul solution. The

soiutioiis i charged with salts c us the sands oy percolation, as will. he to later.

rEhe clarified streng copper solution in settler No. l is electrolyzed in the copper depositing tanks to deposit the copper as the elcctrolytic metal and to regenerate acid for leaching the coppe-L` from the ore. En leaching copper ores with acid solutions iron is always dissolved with the connor. and this iron in the solution plays ari Aiinportant part in the deposition of the copper. Ferrous iron in the electrolyte p u harmless and ma).Y be benefici l, while iron in the clcctrolyt is highlj,Y 'detriment lu order to convert the harmful ferrie :you int-o the harmless ferrous iron, the solution is reduced with sulphur dioxide in the reducer, with sulphur dioxide oliiY 'l roasting sulphide ore or concimi roasting furnace. The reduc from the SO2 reducer` 1r j, he e direct, hut it is prefer-rf 'i'. to also C nto the electoiyiic ineta From the Juf'i reduce per solution ows into t per depositing tanks, Where the eposited as the cleiitrolytic incitar. ii-e simultaneous regeneration ot acid and ferri iron. The solution is passed through the copper depositing tanks at a rale so that ih ferrie iron formed will pre lerahli noi i; f 0.25%, although the amount ot terr' in the eiiluent solution ninjiv raw'. 0.25% is simpl)Y stated con'cui; tical limit. The solution from ine depositing tanks is returned to ihe I.V ducer and 'circulated in a sort ol closedl cuit between the reducer and copper depto# ing tanks to remore the desired uuiozuu o` copper, while at the same time u portion. the advance flow. or the sreani ol` ;ouuioii flowing through the cntirix leaching4 u ud eliwl trolytic circuit, is flowed into :iguaor )l i. 3. to make another completo cyr-le. 'il tails ot' this operation is more falliY de in my Patents No. 1353.095, sont. ef. and 'hl-.. 1.483,056, Fcl). llrl.

l 'f-Jidcnt that by ciiculaliuggf the in :i sort of closed circuit as des/'ru the While accumulating in ilu' i lili or u im ne www While a similar amount of Water is added to make up the volume of solution to its original amount. In this Way the regular leach solution may be kept at any desired standard of purity or impurity, as found best by experience for each particular condition.

The foul solution, high in iron, is then separated ,from the slime in separators No. 4 and No. 5, and the copper precipitated from this foul solution as already. described, preferably 'with hydrogen sulphide, which is capable of precipitating copper from acid solutions and of regenerating an equivalent of acid for the copper precipitated, and this acid is advantageous in producing ferrie iron. The foul solution, with the copper sulphide precipitate, flows into separator No. 6, Where the CUS is separated from the clear solution. The CnS goes to the CnS reducer in the electrolytic circuit. The clear foul high-iron solution Alows into the. feiric iron cells, Where ferrous iron 'in the solution is converted into the ferrie condition, and this ferrie iron solution is then used to leach the ore sand in the percolation tanks. Copper, in some of its combinations in ores, is more susceptible to close extract-ion with a. ferrie salt solution than with a straight acid solution, and when the two are conibined, a very effective solvent is obtained, and a high percentage of extraction of the copper from the sands is practical. in this way the foul solutions, as also the wash Waters, may be used to advantage. The-lean copper-solution frein the percolation tanks is preferably joined with that. 'from the sliines for convenience in precipitation.

En. separating the residue from the solution in separator No. 3, and in the classifier, it is not intended to wash the sands to remove all the soluble copper. The process is the sands, and so that one tank can be under treatment a suilicient time While the other is being filled.

The ferrous iron in the foul copper-barre? solution may be conveniently converted into the ferrie condition by electrolysis,k

:iltho any other method may be used. Elec truly-sis, houf'ever, offers certain advantages, in that the acid resulting from the copper precipitation is a help in converting ferrous iron in the foul solution to ferrie iron by electrolysis, since the ferrie iron is formed to some extent at the expense of 'the acid, and insoluble basic salts are avoided, as in the case of the conversion of the ferrous iron to the ferrie iron in neutral solutions. It has been found diliicult to precipitate the copper by electrolysis, from solutions containing salts of iron, with the sin'mltaneous regeneration of a large amount of ferrie iron in the electrolyte, but When the copper is first precipitated from the solution, the production of ferrie iron is greatly siinplified.

The wat-ei" added to the regular leach solution in the agitation circuit, is preferably added at the classifier in an amount equal to that consumed or diverted from the circuit. An equivalent of foul solution will pass over with the shines, or with the sands into the percolation tanks. lVliile the sands separated in the classiliei may be, Washed to any extent desired, the process is simplitied by passing,` the orc sands from the classifier directly into the percolationtank,

so that further treatment of the sands can from previous usc through the percolation y tanks before letting the solutions go lo waste. In the operation of an electrolytic, or acid regenerative process, in the treatment of sulphide copper ore oi' concentrate, more acid is formed than is used in the regular operation of the process. By ap plying this excess acid for a relatively long time to the large volume of ore in the percolationftanks, the excess acid is largely consumed in doing' useful work in extracting alai'ge percentage of the copper which can be extracted with more or less difficulty, and thus vthe application of the foul 'solutions to the sands in the Apercolation tanks.'

Works to advantage both Ways.

Usually foul solutions, as they are gcnerally discarded, have a potential solvent power for metals, especially if the dissolved metals are precipitated with the simultaneous regeneration of the solvent, such as acid, or feiiic iron, either chemically oi electrolytically. When the shines areI re- -moved from the partly treated ore, the impurity of the solution docs not make so much difference in the percolation treat* nient as when the sliines are not removed. If lthe sands in the percolation tanks contain copper which is soluble in an a idsolution, the simple foul atid solution is applied to lheisands wit-hout any special further treatment, if, howeverjtiie sands con tain copper in a form not readily soluble in a, simpre acid Soin/riorl sach' as Sorce 'toria of sulphide, it ia dciiianle to treat the ordinary ioni solution to convert ferrous iron 'ato erric iron, and thenleach the sands with the acid ferrie iron solution.

The foul solution may be used in a closed circuit between the precipitator and they percolation tanks, and if ferrie sait regeneration is desired, the ferrie iron cells may be included in the circuit, and only the'inore or less dilute wash Waters Wasted from this circuit.

claim:

l. A process of treating copper ores coin prising, agitating the ore with an acid soiution to extract a portion of the copper, separating the copper solution from thc orc and separating the ore sands 'from the ore shines precipitating the copper trom the copper solution obtained by agitation, and 'hen treating the sands by percolation with barren solution from which the copper prec ,itated A ess or" treating; copper orcs conipeising, st itating the ore with an acid soi"tion io extract e portion o? the coi copper solution the ore. sands "the crc sliinea, prcciptatin; tiie copper copper Solution onii inca aj; agitawith flic simultaneous regeneration ot acid, and iiien 'treating the sands by pertion with the resultingA solution to extract another portion of thc copper from the sands.

3. A process of treating copper ores comprising. agitating the ore with an acid solutiorrto extract a portion ot the copper, separating 'the resulting` copper solution corr` taining salts of iron from the ore. and sepa: rating-thc ore sands from thc orc shines, precipitating;- thc copper from the copper .solution containing salts of iron.y treating the resulting depleted copper solution containing salts or" iron to convert the vferrous iron into the ferrie condition. and then treating the sands by percolation 'with said ferrie .salt solution to extract another portion of the copper from the sands.

process of treating copper ores coinprising` affitating thc ore with an acid solution to extract a portion of the copper, separatingr the resulto-tg copper solution coni faits oi iron from the orc and sepathc orc sands troni the, orc alii cs, roiiai'fiacr thc copper troni the copper `th the simultaneous regeneration pcr solution containing salts ot iron to con vert the terre is iron intothe terric condition` and thm treating the, sands hy pel-- colation with fiaid acid ferrie sait solution to extract another portion ot the copper from the sands.

5. A process of treating copper ores conia portion of forming, agr :tft

separating die from the ore and t from the oro sliincs. ing copper solution obtain deposit the coppcr and r then treating the .sand the regenerated acid extract another portion of the coJ the sands.

C. A process of treating copper orc. pricing` agitar j Lhe onl with aci tion to entraiL a portion of t i separating the resulting troni thc orc and @epa from the orc shines iccI r inf;- foppcr .laolutioiyoi t and contamina' of copper and rcycncratc acid t then clec'troiyzrng the tir-,pl t copper solution to conrert the ferrous iron iu the solution into the ferrie condition, 'and thon trcatingr the ore sands i.; p "iin with the regenerated acid anti fcric si', t .in so obtained to exit' another portion o'( the copper from thc sands.

z. )L pr :ess of treating copper rcs l s Gitti itlil i salmi fol' prisingr, agitating the orc with an :tcif tion to extract a portion of the, coppe sep aratinf; the rcsulti g copper solution from the ore and separating the orc sands Yfrom the orc slinics, elcctrolyzing the resulting copper .solution containing Salis oi" iron obtained by agitation to deposit the copper and regenerate acid and icrric iron, ret-urnincr the elcctrolyzed solution to the agitator and repeating thccycle off' leachingr and electrolysis until the copper solution becomes charged with iron and othcr-impurities.y then treating the orc sands by percolation with the foul solution obtained from the cyclic, treatment of the orc by agitation and electrolysis to extract another portion of the copper from the ore sands.

S. A process of treating copper ores coinprising, agitatin;r the ore with an acid solution to extract a portion of the copper, separating the resulting copper @intron from the orc and separating: the ore sands from the ore shines, elcctrolyzing the resultingI copper solution containing salts of iron to deposit the copper and regenerate acid and rerric iron, applying a reducing agent to the electrolyte. circulating a portion of the solution in a closed circuit between the cop-f pcr depositingl tanks and the. rednecr and another portion through the complete agitan tion and electrolytic circuit until the solu' tion becomes charged with iron and other impurities, then diverting a portion of the t'oul solution troni the agitation and electrolytic circuit and precipitating the coppe therefrom, and then treat-ing the ore sandra by percolation with the resulting foul dc- :iii

assesses 9. process of treating copper ores coinpricing, agitating the ore with an scicl sos lutionto eXtra-'ct a portion of the copper, .separating the resulting copper solution containing salts of iron from tlie ore and 'separating,` the ore sands from tire-ore clinics, precipitatingr tlie copper from the resulting copper 'solution with tile siinultsneous regeneration of acid, returning the regenerated acid solution to the agitators and repeating the cycle of solution and precipitation until the solution becomes charged with iron salts and other impurities, then treating tile ore sands by percolation with tlie copper from the foul solution from the percolation tenltsfreturning the solution to the percolation tanks and continuing the cycle of circulation of the solution between the percolation tanks andthe precipitator until tlievcopperin the ore sancls is sufficiently extracted, i

10. A process of treating 'copper ores coruprising, agitating the ,ore with an acicl solution to extract a portion of the copper, separating the resulting copper solution containing salts of iron from the ore and sepaating the ore Santis froml the ore slirnes, precipitating the copper from the resulting vcopper solution, returning the depleted copper solution to the agitators and repeating the cycle ci solution and precipitation luntil the solution becomes charged with iron salts anti other impurities, then treat-ing said foul solution to convert ferrous iron into ierric ironyand treating" the ore sands by percolaon with theres-'uiting 'foul solution containing ferrie iron, precipitating the copper from the foul solution from tlie percolation tank, again treating the depleted foul solution to convert' ferrous iron to ferrie iron and. returning thefoul .iterriciron solution Ato tile percolation tank, and continuing the cycle of percolation, precipitation, and regeneration of ferric iron until the copper in tlie ore sands is suicientlyextrsctetl.,

il, process of treating copper ores cornprising, egitating the ore with an aei solutionv to extract s. portion of the copper, separating the resulting copper solution from the ore and-separating the ore sands from the ore sliines, Washing the slimes to remove i-lis soluble copper therefrom, electrolyzing the copper solution from the agitator to deposit the copper and regenerate acid, returning the regenerated 'acid solution to the agita-tor and repeating the cycle ofsolution and electrolysis until the solution becomes fouled with impurities, thentreating the ore; sentis "foy percolation with the foul solution from the electrclytic'circuit, precipitating the copper in tire foul solution from tli'e percolation tanks anni from the slime Wash Water,

eno. applying the precipitated copper so 0btuinetl to the yelectrolytel whereby tliecopper ot tile precipitate is converted into the electrolytic metal.

12. process oi treating copper ores cornprising, agitatinp,` the ore with an acid solution. to extract portion of the copper, separetino the resultinglr copper solution from the ore, then adding wash Water to the ore to malte up for that lost or wasted in the oplill eration of the process, and then separating theore sands from the ore slimes, precipitating the copper from tlie copper solution from the agitator, anti then treating the sands by percolation with the depleted cop- 30 per solution from the agitator to extract anresulting foul solution, precipitsting 'tire other portion of the copper from the ore sands.

13. A process ot treating copper orcs comorising, agitating the ore with un scid solu- 535 tion to extract a portion of the copper, separating the resulting copper solution Jfrom the ore and separating the ore sends from tlie ore slimes, placing the ore sands only partly Washed and still containing copper in im' solution in a percolation tanks precipitating the co per from the copper solution 'from tlie agitator and repeating the' cycle of clolu- 'tion'and precipitation until 'the solution in the agitation circuit becomes fouled with im- 95 purities, then treating the ore sands in the percolation ,tank with the "foul solution from the agitation circuit to extract another portion of the copper from the ore sands.

lll. A process o treating ores of metals mi comprising, passing' 'tlie pnlyerizecl ore snol the solvent for the metals coimter-currently through a, series of agitation units each unit comprising an agitator and u separator enti. concurrently through cach ot the agitation wi units of ,agitator and separator comprising the :series of agitation units.

i5. t process of treating ores roil metals comprising', passing the pulverizecl ore and the solvent for the metals counter-currently n@ through a series of agitation units each unit comprising an agitator and e, separator for the ore and solution snfl concurrently tlirouli each of the agitation units comprising tus series, separating the strong :instel M5 solution from the ore, precipitating the metals from the solution, and returning the barren solution tothe or lo. .A process of treatin orcs of metals comprising'nassing the puiverizel ore an 12% the solvent liir the metsls counter-currently through a series of agitation units each comprising an agitator and a separator for the ore ancl solution and concurrently tlirou h each ot' the agitation units comprising t c 12 series, separa-ting the metal solution from the ore and separating the ore sands from the ore sliines, precipitating the metals from the solution, and then treating the sands by percolation with said solution to extract anim o? "alle copper from 'the or@ vviosly used to ofatruct he copper iron, #glio uxoiassifnd ore by agitation.

o; oros of mesll` 20. ,in iii q, rmimonz of copper oros in ugitfiiing pulvesized ore which o porion of ille copper is roaily for the 'nials fo extra@ soluble in :i reluivoiy short time and anliv meollo sep uing die resul'- other portion soluble by prolonged breatoie anu sepa nient. 'die process comprising. subjecting the 40 ore sands roio ill@ ore slinie. uncm, "fild pulverized ore totheactionof the mll 'from .flio solutioin Solvent by agitation to extract the readily fron soluiiou ifo re- "e copper, then classifying the partly ion for ih@ morali Larri or@ into sands and slimes, and thon by piicolu'on si. @cling 'lie sands for :i relatively long *5 if 'io the; action of the Solvent by percolaproccss of trating copper ores Y g, ziginting the ore wii'li au avid on fo extract a portion of the copper, 50 :w'izw'iusf tlif resulting copper solution so om?, Sepuiuling lie oro Sands ou, elorirolyzing the result Solution #o deposit the copper aioiil. r, uruing tho regen- 55 iou to the agitator to trent ."ufi repcziing lie cycle of solu- -lorlrolysis until lic solution liecoines ioiiled willi. impurities, tiefziing the partly treated or@ ands Wih 'the foul solu- 0 tion. Cliemiculiy preriipi'iuiing the copper from the foul soluiion. lion elecrolyzing the soluion to couv W "i rous iron to ferric iron, and than relui'izz" lozii solution to tlv partly treated sands.

VLLM E. GREEAf/f LT. 

